(a) Field of the Invention
The present invention relates to a carbon nanotube film, and more particularly, to a method for fabricating a carbon nanotube film floating on a bottom, and a sensor based on the carbon nanotube film.
(b) Description of the Related Art
A carbon nanotube is a new tubular material having hexagons of six carbons connected with one another into the form of a tube, which has superior electrical conductivity and thermal conductivity, as well as high strength.
The carbon nanotube has highly sensitive electrical properties, and therefore is applicable to sensors for the detection of various materials, such as chemical gas molecules and biological molecules, using these properties. Concretely, various sensors using carbon nanotube films are used to detect DNAm protein, bacteria, gas molecules, etc.
A sensor using carbon nanotubes may be formed of nanotubes or a nanotube network. Particularly with a sensor formed of a nanotube network, the signal-to-noise ratio (SNR) and the detection range of materials can be improved, and the sensor can be easily applied to a variety of devices.
Meanwhile, in the case of the sensor using carbon nanotubes where the carbon nanotubes are disposed on the bottom surface of a substrate, etc. with a convection velocity close to zero, the mass transport of a target material to be detected towards the surfaces of the carbon nanotubes becomes inefficient, thus limiting the improvement of sensitivity and response time of the sensor. Moreover, the performance of the sensor depends upon the conditions of the surface of the substrate, for example, electrification of the surface, chemical species, functional groups, and so on.
A recent research reported that the sensitivity and response time of a carbon nanotube sensor can be improved by forming the sensor to float on the bottom surface of a substrate, etc. The carbon nanotubes floating on the bottom has a binding surface 2 times or more larger than in the conventional art, and increases the convection and diffusional flow of a target material towards the carbon nanotubes. For example, carbon nanotubes floating 12.5 μm on the bottom show a rate of bond formation about 2.6 times higher than in the conventional art.
However, it is difficult to align the carbon nanotubes efficiently by the method of fabrication for a carbon nanotube film floating on a bottom, which is known from the prior art, and the fabrication process can be complicated because the process is incompatible. Moreover, it is difficult to control the density of the carbon nanotubes, and a film patterning process is required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.